Extruders for extruding plastic material from a molten stream of plastic material have been known and used for some time. One particular use of such an extruder is in connection with a pelletizer assembly, which is mounted to the end of the extruder. In such a combination of an extruder and a pelletizer, a die having a plurality of holes therein is mounted at the end of the extruder and at the entrance to the pelletizer assembly and forms part of both. The pelletizer then includes a rotating cutter assembly having cutting blades positioned adjacent the die face from which streams of molten plastic material flow. The rotating cutter assembly cuts the streams of plastic material into pellets of various sizes depending upon the extrusion flow rate through the holes in the die and the speed of rotation of the cutter assembly.
Also, the flow of water through the chamber serves to carry the pellets away from the chamber.
In such a combined extruder and pelletizer assembly it is desirable to provide means for facilitating a smooth flow of the plastic material from the extruder to the die holes in the die. Also it is desirable to provide means for gaining easy access to the chamber for servicing the pelletizer, such as to replace worn cutting blades of the cutter assembly, to generally observe the formation of pellets by the rotating cutter assembly, and to clean the die.
It is also desirable to provide a long useful life for the cutting blades of the cutter assembly and die. That is to say, it is desirable to provide cutting blades that will last a long time. In addition, it is desirable to provide some means for automatically readjusting the position of the cutter assembly adjacent the die face as the space between the cutter assembly and the die face increases due to wear of the cutting blades. In this respect, it is desirable to keep the cutting blades juxtaposed to the die face to ensure clean cutting of the streams of plastic material into pellets.
U.S. Pat. No. 4,529,370 illustrates one example of a conventional underwater pelletizer.
Another example of a conventional underwater pelletizer is shown in U.S. Pat. No. 5,059,103. Some conventional components for pelletizers are shown in U.S. Pat. Nos. 4,621,996; 5,403,176; 5,624,688; and 6,332,765.